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Make lwgeom_subdivide use lwgeom_intersection for clipping #281

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dbaston commented Jul 31, 2018

Thjs PR updates lwgeom_subdivide to use lwgeom_intersection for
clipping instead of lwgeom_clip_by_rect. No tests are changed.

lwgeom_clip_by_rect describes itself as clipping in a "fast but possibly
dirty way." This is not a good fit for lwgeom_subdivide, a primary use of
which is the optimization of point-in-polygon processes. That application
requires that the area covered by the subdivided geometry be the same as
the area covered by the original geometry, which in turn requires that a
robust intersection routine be used.

As discussed in #279 . Merging this allows lwgeom_clip_by_rect to be
reverted to its 2.4 state without affecting lwgeom_subdivide.

Make lwgeom_subdivide use lwgeom_intersection for clipping
lwgeom_clip_by_rect describes itself as clipping in a "fast but possibly
dirty way." This is not a good fit for lwgeom_subdivide, a primary use of
which is the optimization of point-in-polygon processes. That application
requires that the area covered by the subdivided geometry be the same as
the area covered by the original geometry, which in turn requires that a
robust intersection routine be used.
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Travis failure is from MVT tests; subdivide tests are OK.

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dbaston commented Jul 31, 2018

Travis failure is from MVT tests; subdivide tests are OK.

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Any objections to this?

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dbaston commented Jul 31, 2018

Any objections to this?

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strk commented Aug 1, 2018

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